Singulation of optical waveguide materials

ABSTRACT

Methods for singulating an optical waveguide material at a contour include directing a first laser beam onto a first side of the optical waveguide material to generate a first group of perforations in the optical waveguide material. A second laser beam is directed onto a second side of the optical waveguide material to generate a second group of perforations in the optical waveguide material. The second side is opposite the first side. The first group of perforations and the second group of perforations define a perforation zone at the contour. A third laser beam is directed at the perforation zone to singulate the optical waveguide material at the perforation zone.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. application Ser. No.17/126,574, filed on Dec. 18, 2020, which claims priority to U.S.Application Ser. No. 62/951,261, filed on Dec. 20, 2019, which areincorporated by reference herein in their entity.

TECHNICAL FIELD

This disclosure relates to singulating optical waveguide materials.

BACKGROUND

Traditional methods that use milling or water jets to cut opticalsubstrates can cause stresses in the substrate. Excess substrate stresscan cause pieces of the substrate to separate along paths that are notin accordance with the singulation program.

SUMMARY

Innovative aspects of the subject matter described in this specificationinclude methods, apparatus, and systems for singulating an opticalwaveguide material at a contour. A first laser beam is directed onto afirst side of the optical waveguide material to generate a first groupof perforations in the optical waveguide material. A second laser beamis directed onto a second side of the optical waveguide material togenerate a second group of perforations in the optical waveguidematerial. The second side is opposite the first side. The first group ofperforations and the second group of perforations define a perforationzone at the contour. A third laser beam is directed at the perforationzone to singulate the optical waveguide material at the perforationzone.

Among others, the benefits and advantages of the embodiments disclosedherein include the manufacture of optical waveguides for monocular orbinocular headsets having enhanced visual qualities and performancecompared to traditional methods. The embodiments provide the generationof complex shapes having demanding geometries for critical opticalalignment from birefringent substrates of varying thickness and indicesof refraction. The incising of a localized region surrounding a criticalarea of interest provides reduced wafer-level stress compared totraditional methods. Thus stress cracks and fractures along thepreferential crystalline internal structure are reduced compared totraditional methods, and the process yield is increased.

The details of one or more embodiments of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other potential features, aspects, and advantages ofthe subject matter will become apparent from the description, thedrawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a side view of a system that forms a relief patternon a substrate.

FIG. 2A illustrates a cross section of a laser directing a laser beamonto a side of an optical waveguide material.

FIG. 2B illustrates a side view of a system that forms a singulatedcontour on a substrate.

FIG. 3 illustrates a planar view of an optical waveguide material.

FIG. 4A illustrates a singulated optical waveguide material.

FIG. 4B illustrates a cross section of a first set of perforations in anoptical waveguide material.

FIG. 4C illustrates a cross section of a second set of perforations inan optical waveguide material.

FIG. 4D illustrates a planar view of a singulation path in an opticalwaveguide material.

FIG. 4E illustrates a planar view of a singulation path in an opticalwaveguide material.

FIG. 5 illustrates a process for singulating an optical waveguidematerial.

DETAILED DESCRIPTION

FIG. 1 illustrates a system 100 that forms a relief pattern on asubstrate 102. The substrate 102 can be coupled to a substrate chuck104. In some embodiments, the substrate chuck 104 includes a vacuumchuck, a pin-type chuck, a groove-type chuck, or an electromagneticchuck. In some embodiments, the substrate 102 and the substrate chuck104 are further positioned on an air bearing 106. The air bearing 106provides motion about the X, Y, or Z-axes. In some embodiments, thesubstrate 102 and the substrate chuck 104 are positioned on a base. Theair bearing 106, the substrate 102, and the substrate chuck 104 can alsobe positioned on a stage 108. In some embodiments, a robot 110(including a motor) positions the substrate 102 on the substrate chuck104.

The system 100 further includes an imprint lithography flexible coatedresist template 112 that is coupled to one or more rollers 114 a, 114 b,114 c, 114 d, 114 e. The rollers 114 a, 114 b, 114 c, 114 d, 114 eprovide movement of the flexible coated resist template 112. Suchmovement can selectively provide different portions of the flexiblecoated resist template 112 in superimposition with the substrate 102. Insome embodiments, the flexible coated resist template 112 includes apatterning surface that includes a group of features, e.g., spaced-apartrecesses and protrusions. The patterning surface can define any originalpattern that defines the basis of a pattern to be formed on substrate102. In some embodiments, the flexible coated resist template 112 iscoupled to a template chuck, e.g., a vacuum chuck, a pin-type chuck, agroove-type chuck, or an electromagnetic chuck.

The system 100 can further include a fluid dispenser 120. The fluiddispenser 120 can be used to deposit a polymerizable material on thesubstrate 102. The polymerizable material can be positioned upon thesubstrate 102 using drop dispense, spin-coating, dip coating, chemicalvapor deposition, physical vapor deposition, thin film deposition, orthick film deposition. The system 100 can further include an energysource 122 to direct energy (such as from a laser beam) towards thesubstrate 102. In some embodiments, the rollers 114 and the air bearing106 are configured to position a desired portion of the flexible coatedresist template 112 and the substrate 102 in a desired positioning. Thesystem 100 can be regulated by a controller in communication with theair bearing 106, the rollers 114, the fluid dispenser 120, or the energysource 122, and may operate on a computer readable program stored in amemory.

FIG. 2A illustrates a cross section of a laser beam 204. The laser beam204 is emitted by a laser 200 and directed onto a first side 208 of anoptical waveguide material 212. The optical waveguide material 212 is aspatially inhomogeneous material used for manufacturing an opticalwaveguide for guiding light, for example, in an augmented realityheadset. The optical waveguide material 212 restricts a spatial regionin which light can propagate. In some embodiments, the optical waveguidematerial 212 is less than 1 mm thick. In some embodiments, the opticalwaveguide material 212 is a crystalline material having a refractiveindex greater than 1.6. For example, the optical waveguide material 212can be formed of one or more of LiNbO₃, LiTaO₃, or SiC.

The laser 200 illustrated in FIG. 2A is configured to perforate theoptical waveguide material 212 at the contour 224. The contour 224 canbe defined in a computer image used for manufacturing an opticaleyepiece, such as for an augmented reality headset. The contour 224defines a shape of a first piece 304 of the optical waveguide material212 that is to be singulated from a second piece 308 of the opticalwaveguide material 212 for manufacturing an optical device. For example,the first piece 304 can be used for manufacturing an optical eyepiece.The first piece 304 and the second piece 308 of the optical waveguidematerial 212 are illustrated in FIG. 3 .

Prior to singulating the optical waveguide material 212, a first laserbeam (such as the laser beam 204) is directed from a first laser (suchas the laser 200) onto the optical waveguide material 212 to incise aset of fiducial markers 232 in the optical waveguide material 212. Insome embodiments, the first laser beam 204 is directed onto the opticalwaveguide material 212 by the laser 200. In other embodiments, the firstlaser beam 204 is directed by a controller, the robot 100, or a motor.In some embodiments, the first laser 200 is a diode-pumped laser. Forexample, the first laser 200 can be a solid-state laser that uses adiode-pumped, mode locked system with ultra-short pulses and a highpulse energy. In some embodiments, a wavelength of the first laser beam204 is in a range from 750 nm to 1500 nm.

The set of fiducial markers 232 are in a spaced relationship with thecontour 224 and are used as points of reference or a measure. Forexample, the computer image used for manufacturing an eyepiece or otheroptical device can define the fiducial markers 232 to monitor theplacement of the optical waveguide material 212 and align the opticalwaveguide material 212 with the first laser 200. The contour 224 andfiducial markers 232 can be programmed such that the set of fiducialmarkers 232 are in a spaced relationship with the contour 224, definedby coordinates and a predefined separation between the contour 224 andthe fiducial markers 232. The contour 224 and fiducial markers 232together define a singulation pattern or program for manufacturing anoptical device.

To singulate the optical waveguide material 212 at the contour 224, thefirst laser beam 204 is directed from the first laser 200 onto a firstside 208 of the optical waveguide material 212. The first laser beam 204generates a first set of perforations 220 in the optical waveguidematerial 212. The first set of perforations 220 is illustrated anddescribed in more detail with reference to FIG. 4B. In some embodiments,the first laser beam 204 generates the first set of perforations 220 bychemically altering a first portion of the optical waveguide material212 at the contour 224. The first portion of the optical waveguidematerial 212 corresponds to the first set of perforations 220. The firstlaser beam 204 can induce a photolytic or pyrolytic mechanism ofmaterial alteration of the first portion of the optical waveguidematerial 212 at the contour 224. The first portion of the opticalwaveguide material 212 can photochemically decompose as a result of therelatively higher excitation energies breaking chemical bonds in thefirst portion of the optical waveguide material 212, leaving aninhomogeneous residual material at the site of exposure. The firstportion of the optical waveguide material 212 is left weaker, morebrittle, or more discontinuous compared to before the chemicalalteration. The first portion of the optical waveguide material 212 canalso decompose thermally, depending on the specific material, the laserenergy, or the pulse rate.

In some embodiments, the first laser beam 204 generates the first set ofperforations 220 by ablating the first portion of the optical waveguidematerial 212 at the contour 224, such that the first set of perforations220 extend through the optical waveguide material 212 from the firstside 208 to the second side 216, as illustrated and described in moredetail with reference to FIG. 4B. The diameter of each perforation ofthe first set of perforations 220 can vary along a length of theperforation. The chemical alteration of the first portion of the opticalwaveguide material 212 at the contour 224 takes place before theablation.

In some embodiments, a focus offset of the first laser beam 204 is in arange from −0.3 mm to 0.3 mm. The focus offset of the first laser beam204 is sometimes referred to as the z-offset. The focus offset settingof the first laser beam 204 is used to direct (focus) the first laserbeam 204 onto the contour 224. In some embodiments, a number of pulsesper burst of the first laser beam 204 is in a range from 4 to 15. Thenumber of pulses per burst can be adjusted by the system 250, which isillustrated and described in more detail with reference to FIG. 2B, toadjust a cutting rate or sharpness of cut in accordance with thephysical characteristics of the optical waveguide material 212. Thenumber of pulses per burst aggregates all the pulses in a burst as wellthe equivalency of the pulses to the burst energy from the first laser200. When the number of pulses per burst is relatively smaller, thedifference in energy levels between a first pulse and a second pulse isrelatively greater compared to when a relatively greater number ofpulses per burst is used, where the difference in the energy levelsbetween pulses is relatively smaller. In some embodiments, a power ofthe first laser beam 204 is in a range from 45 W to 55 W. The power ofthe first laser beam 204 is an important factor affecting penetrationinto the optical waveguide material 212 and the generation of the firstset of perforations 220. The rate of generation of the first set ofperforations 220 increases as the power of the first laser beam 204increases.

A computer numerically controlled speed of the first laser beam 204 canbe in a range from 4 m/minute to 15 m/minute. The computer numericallycontrolled speed of the first laser beam 204 can be adjusted by asingulation program executed by the system 250 in FIG. 2B formanufacturing an optical eyepiece. For example, the system 250 in FIG.2B can execute a computer numerical control (CNC) configuration thatdefines the manufacturing task (singulation) to be performed and thecutting speed of the first laser 200. The CNC configuration is a codedprogram set of instructions that controls the motor 254, the first laser200, or other machine tool movement to meet the manufacturingspecifications.

The optical waveguide material 212 is rotated about an axis 228 in aplane of the optical waveguide material 212, such that a second side 216of the optical waveguide material 212 faces a second laser 236. Forexample, the plane of the optical waveguide material 212 can be theplane of the first side 208. The second side 216 of the opticalwaveguide material 212 is opposite the first side 208. The opticalwaveguide material 212 can be rotated by a motor 254, of the system 250in FIG. 2B. For example, the robot 110, illustrated and described withreference to FIG. 1 , can include the motor 254. In some embodiments,the first laser 200 and the second laser 236 are the same. A frequencyof the first laser 200 and the second laser 236 can be in a range from100 kHz to 300 kHz. The frequency of the first laser 200 and the secondlaser 236 specifies the number of laser pulses per second. The amount ofenergy per photon increases as the frequency of the first laser 200 orthe second laser 236 increases.

A second laser beam is emitted by the second laser 236 and directed ontothe second side 216 of the optical waveguide material 212 to generate asecond set of perforations 404 in the optical waveguide material 212.The second set of perforations 404 is illustrated with reference to FIG.4A. The first set of perforations 220 and the second set of perforations404 define a perforation zone 412 at the contour 224, as illustrated inFIG. 4A. In some embodiments, the second laser beam generates the secondset of perforations 404 by chemically altering a second portion of theoptical waveguide material 212 at the contour 224. The second portioncorresponds to the second set of perforations 404. In some embodiments,the second laser beam generates the second set of perforations 404 byablating the second portion of the optical waveguide material 212 at thecontour 224. The diameter of each perforation of the second set ofperforations 404 can vary along a length of the perforation from thesecond side 216 to the first side 208.

A third laser beam is emitted by the third laser 240 and directed at theperforation zone 412 to singulate the optical waveguide material 212 atthe perforation zone 412. In some embodiments, the third laser 240 is acarbon dioxide (CO₂) laser. In other embodiments, the third laser 240 isa radio frequency (RF)-excited, pulsed CO₂ separation laser. In someembodiments, the third laser beam includes infrared light having awavelength in a range from 5 μm to 15 μm. In some embodiments, a focusoffset range of the third laser beam is less than 5 mm. The focus offsetor z-offset of the third laser beam is used to direct (focus) the thirdlaser beam onto the perforation zone 412 for singulating the opticalwaveguide material 212. In some embodiments, a frequency of the thirdlaser beam is in a range from 10 kHz to 20 kHz. The frequency of thethird laser specifies the number of laser pulses per second. The amountof energy per photon decreases as the wavelength of the third laser beamincreases. In some embodiments, a power of the third laser beam is in arange from 10 W to 35 W. The rate of singulation of the opticalwaveguide material 212 increases as the power of the third laser beamincreases.

FIG. 2B illustrates a side view of a system 250 that forms a singulatedcontour on a substrate. The system 250 includes the substrate chuck 104and air bearing 106, illustrated and described in more detail withreference to FIG. 1 . The air bearing 106 provides motion about the X,Y, or Z-axes. The air bearing 106 and the substrate chuck 104 arepositioned on the stage 108. In some embodiments, the motor 254positions the optical waveguide material 212 on the substrate chuck 104.The stage 108 and the optical waveguide material 212 are illustrated anddescribed in more detail with reference to FIGS. 1 and 2A. The system250 further includes a laser module 244 driving the first laser 200, thesecond laser 236, and the third laser 240. The first laser 200, thesecond laser 236, and the third laser 240 are illustrated and describedin more detail with reference to FIG. 2A.

In some embodiments, the stage 108 illustrated in FIG. 2B is a CNC stagethat can be moved along one or more directions of motion (axes) bymotors in accordance with a singulation program. The system 250 can havea stationary laser module 244 attached to the first laser 200, thesecond laser 236, and the third laser 240. In some embodiments, thestage 108 is a non-moving, stationary stage and the system 250 includesa CNC laser module 244. The CNC laser module 244 can move each laserusing rapid positioning movements, straight line motion, or circularmotion in accordance with the singulation program. In other embodiments,the system 250 includes a CNC stage 108 and a CNC laser module 244 thateach operate in accordance with the singulation program.

FIG. 3 illustrates a planar view of an optical waveguide material 212.The optical waveguide material 212 is illustrated and described in moredetail with reference to FIG. 2A. An example singulation pattern orprogram for manufacturing an optical device using the optical waveguidematerial 212 shown in FIG. 3 includes six pieces (for example, piece304) to be singulated from the optical waveguide material 212. Eachpiece 304 can be used to manufacture an optical eyepiece, for example,for an augmented reality headset. A contour 224 defines a shape of eachpiece 304 of the optical waveguide material 212 to be singulated. Thecontour 224 is illustrated and described in more detail with referenceto FIG. 2A. The contour 224 is defined by an example singulation patternor program, for example, stored in a computer-readable memory of thesystem 250, illustrated and described in more detail with reference toFIG. 2B.

A first laser beam 204 is directed from a first laser 200 onto a firstside 208 of the optical waveguide material 212 to incise boundarymarkers 316, 320 on the first side 208. The first laser 200, the firstlaser beam 204, and the first side 208 are illustrated and described inmore detail with reference to FIG. 2A. The boundary markers 316, 320 areincised prior to directing the first laser beam 204 onto the first side208 of the optical waveguide material 212 to generate the first set ofperforations 220 are illustrated and described in more detail withreference to FIG. 3 . The first set of perforations 220 are illustratedand described in more detail with reference to FIG. 4A. The contour 224is located between the boundary markers 316, 320. The boundary markers316, 320 decrease wafer-level stresses impacting the optical waveguidematerial 212 from the surface interaction of the first laser beam 204.The boundary markers 316, 320 define individual, localized regionssurrounding the critical areas of interest, where the contour 224 lies.By reducing and localizing the wafer-level surface stress to thecritical areas of interest, stress cracks and fractures along thepreferential crystalline internal structure are decreased and processyields are increased, compared to traditional methods.

To singulate the optical waveguide material 212 at the contour 224, thefirst laser beam 204 is directed from the first laser 200 onto the firstside 208 of the optical waveguide material 212 to generate the first setof perforations 220. A motor 254 is configured to rotate the opticalwaveguide material 212 about an axis 228 in a plane of the opticalwaveguide material 212, such that the second side 216 of the opticalwaveguide material 212 faces the second laser 236. The axis 228, thesecond side 216, and the second laser 236 are illustrated and describedin more detail with reference to FIGS. 2A and 4B.

Responsive to rotating the optical waveguide material 212, the motor 254positions the optical waveguide material 212, such that the fiducialmarkers 232 are in a spaced relationship with the contour 224. Thefiducial marker 232 is illustrated and described in more detail withreference to FIGS. 2A and 4B. In some embodiments, an air bearing 106moves the optical waveguide material 212 laterally on a substrate chuck104, such that the fiducial markers 232 are in the spaced relationshipwith the contour 224. The air bearing 106 and substrate chuck 104 areillustrated and described in more detail with reference to FIGS. 1 and2B.

A second laser beam is directed from the second laser 236 onto thesecond side 216 of the optical waveguide material 212. The second laserbeam generates a second set of perforations (for example, the second setof perforations 404, illustrated and described in more detail withreference to FIG. 4A) in the optical waveguide material 212. The secondside 216 of the optical waveguide material 212 is opposite the firstside 208. The first set of perforations 220 and the second set ofperforations 404 define a perforation zone (for example, the perforationzone 412, illustrated and described in more detail with reference toFIG. 4A) at the contour 224. The contour 224 thus defines a shape of afirst piece 304 of the optical waveguide material 212 to be singulatedfrom a second piece 308 of the optical waveguide material 212.

A third laser beam is directed from a third laser (for example, thethird laser 240, illustrated and described in more detail with referenceto FIG. 3 ) at the perforation zone 412 to singulate the opticalwaveguide material 212 at the perforation zone 412.

FIG. 4A illustrates a singulated optical waveguide material 212. Theoptical waveguide material 212 is illustrated and described in moredetail with reference to FIG. 2A. The optical waveguide material 212 issingulated at the contour 224 to separate a first piece of the opticalwaveguide material 212 from a second piece 308. The contour 224 isillustrated and described in more detail with reference to FIG. 2A. Afirst laser beam is directed from the first laser 200 onto the firstside 208 of the optical waveguide material 212 to generate the first setof perforations 220 in the optical waveguide material 212. The firstlaser 200, first laser beam 204, first side 208, and first set ofperforations 220 are illustrated and described in more detail withreference to FIG. 2A. The first laser beam 204 is moved along thecontour 224, such that a distance 416 between a consecutive pair ofperforations of the first set of perforations 220 is in a range from 3.5μm to 8.3 μm.

The second laser beam is directed from the second laser 236 onto thesecond side 216 of the optical waveguide material 212 to generate thesecond set of perforations 404 in the optical waveguide material 212.The second laser 236 and second side 216 are illustrated and describedin more detail with reference to FIG. 2A. In some embodiments, eachperforation of the first set of perforations 220 or the second set ofperforations 404 has a maximum diameter less than 10 μm. In someembodiments, the second set of perforations 404 is generated, such thata spacing 408 between the first set of perforations 220 and the secondset of perforations 404 is less than a specified accuracy tolerance. Inone example, when the system 250 includes a CNC laser module 244, thespecified accuracy tolerance of the second laser 236 is used. When thesystem 250 includes a CNC stage 108, the specified accuracy tolerance ofthe CNC stage 108 can be used. The specified accuracy tolerance refersto the total allowable error between the intended position of the secondlaser beam (specified by the singulation pattern or program) and theactual position on the optical waveguide material 212 that the secondlaser beam contacts. The specified accuracy tolerance can be representedas a permissible error off of a nominal specification. In someembodiments, the specified accuracy tolerance of the second laser 236 isless than 25 μm and the spacing 408 is less than 15 μm.

The first set of perforations 220 and the second set of perforations 404define a perforation zone 412 at the contour 224. The perforation zone412 is located between the first set of perforations 220 and the secondset of perforations 404. The first laser beam 204 and second laser beamare directed at the optical waveguide material 212, such that theperforation zone 412 aligns with the contour 224 and the opticalwaveguide material 212 can be singulated at the contour 224.

The optical waveguide material 212 is singulated at the contour 224 bydirecting a third laser beam from the third laser 240 at the perforationzone 412. The third laser 240 is illustrated and described in moredetail with reference to FIG. 2A. The third laser beam singulates theoptical waveguide material 212 by heating the optical waveguide material212 at the perforation zone 412 to expand the first set of perforations220 and the second set of perforations 404.

FIG. 4B illustrates a cross section of the first set of perforations 220in the optical waveguide material 212. The cross section illustrated inFIG. 4B includes the optical waveguide material 212, the first side 208,the second side 216, the contour 224, and the fiducial marker 232,described in more detail with reference to FIGS. 2A and 4A.

FIG. 4C illustrates a cross section of the second set of perforations404 in the optical waveguide material 212. The cross section illustratedin FIG. 4C shows a position of the optical waveguide material 212 afterthe optical waveguide material 212 has been rotated such that the secondside 216 faces the second laser 236. The cross section illustrated inFIG. 4C includes the optical waveguide material 212, the first side 208,the second side 216, the contour 224, and the fiducial marker 232,described in more detail with reference to FIGS. 2A and 4A.

FIG. 4D illustrates a planar view of a singulation path 450 in anoptical waveguide material 212. The portion of the optical waveguidematerial 212 illustrated in FIG. 4D includes the first set ofperforations 220, the second set of perforations 404, and theperforation zone 412, described in more detail with reference to FIG.4A. During singulation of the optical waveguide material 212, the twopieces of the optical waveguide material 212 can be separated from eachother along one of multiple singulation paths. A particular singulationpath connects perforations of the first set of perforations 220 and thesecond set of perforations 404, such that the two pieces of the opticalwaveguide material 212 are separated from each other along theparticular singulation path. For example, the two pieces of the opticalwaveguide material 212 in FIG. 4D are separated from each other alongthe singulation path 450.

FIG. 4E illustrates a planar view of a singulation path 454 in anoptical waveguide material 212. The portion of the optical waveguidematerial 212 illustrated in FIG. 4E includes the first set ofperforations 220, the second set of perforations 404, and theperforation zone 412, described in more detail with reference to FIG.4A. The two pieces of the optical waveguide material 212 in FIG. 4E areseparated from each other along the singulation path 454. In otherembodiments, a singulation path can traverse multiple sets ofperforations. For example, a singulation path can connect a firstperforation of the first set of perforations 220, a second perforationof the second set of perforations 404, and a third perforation of thefirst set of perforations 220.

FIG. 5 illustrates a process for singulating an optical waveguidematerial 212 at a contour 224. The optical waveguide material 212 andcontour 224 are illustrated and described in more detail with referenceto FIG. 2A. In some embodiments, the process is performed by the system250, illustrated and described in more detail with reference to FIG. 2B.

In step 504, a first laser beam 204 from a first laser is directed ontoa first side 208 of the optical waveguide material 212 to generate afirst set of perforations 220 in the optical waveguide material 212. Thefirst laser 200, first laser beam 204, first side 208, and first set ofperforations 220 are illustrated and described in more detail withreference to FIG. 2A. In some embodiments, the first laser beam 204generates the first set of perforations 220 by chemically altering afirst portion of the optical waveguide material 212 at the contour 224.The first portion of the optical waveguide material 212 corresponds tothe first set of perforations 220. For example, the first laser beam 204can induce a photolytic or pyrolytic mechanism of material alteration ofthe first portion of the optical waveguide material 212 at the contour224. In some embodiments, the first laser beam 204 generates the firstset of perforations 220 by ablating the first portion of the opticalwaveguide material 212 at the contour, such that the first set ofperforations 220 extend through the optical waveguide material 212 fromthe first side 208 to the second side 216.

In step 508, a second laser beam from a second laser 236 is directedonto a second side 216 of the optical waveguide material 212 to generatea second set of perforations 404 in the optical waveguide material 212.The second laser 236 and second side 216 are illustrated and describedin more detail with reference to FIG. 2A. The second set of perforations404 is illustrated and described in more detail with reference to FIG.4A. The second side 216 is opposite the first side 208. The first set ofperforations 220 and the second set of perforations 404 define aperforation zone 412 at the contour 224. The perforation zone 412 isillustrated and described in more detail with reference to FIG. 4A.

In step 512, a third laser beam is directed from a third laser 240 atthe perforation zone 412 to singulate the optical waveguide material 212at the perforation zone 412. The third laser 240 is illustrated anddescribed in more detail with reference to FIG. 2A. The third laser beamsingulates the optical waveguide material 212 by heating the opticalwaveguide material 212 at the perforation zone 412 to expand the firstset of perforations 220 and the second set of perforations 404. Theprocess of FIG. 5 was used to manufacture optical waveguides using a 150mm wafer (the optical waveguide material 212). The resulting opticalwaveguides were found to have no internal cracks or fractures from heator stress. Moreover, the optical waveguides had reduced edge defectlevels and increased area usage over the optical waveguide material 212,compared to traditional methods.

In additional embodiments, the second laser is configured to emit thesecond laser beam to generate the second set of perforations, such thata spacing between the first set of perforations and the second set ofperforations is less than a specified accuracy tolerance. The specifiedaccuracy tolerance is less than 25 μm and the spacing is less than 15μm.

In some embodiments, the third laser is configured to emit the thirdlaser beam to singulate the optical waveguide material by heating theoptical waveguide material at the perforation zone to expand the firstset of perforations and the second set of perforations.

In some embodiments, the first laser and the second laser are the same,and a frequency of the first laser is in a range from 100 kHz to 300kHz.

In some embodiments, the contour defines a shape of a first piece of theoptical waveguide material to be singulated from a second piece of theoptical waveguide material.

In some embodiments, the optical waveguide material includes acrystalline material having a refractive index greater than 1.6.

In some embodiments, the third laser is a CO₂ laser, and a wavelength ofthe third laser beam is in a range from 5 μm to 15 μm.

In some embodiments, the first laser is a diode-pumped laser, and awavelength of the first laser beam is in a range from 750 nm to 1500 nm.

In some embodiments, the optical waveguide material is less than 1 mmthick and each perforation of the first set of perforations and thesecond set of perforations has a maximum diameter less than 10 μm.

In some embodiments, a distance between a consecutive pair ofperforations of the first set of perforations is in a range from 3.5 μmto 8.3 μm.

In some embodiments, a focus offset of the first laser beam is in arange from −0.3 mm to 0.3 mm, and a number of pulses per burst of thefirst laser beam is in a range from 4 to 15.

In some embodiments, a power of the first laser beam is in a range from45 W to 55 W, and a computer numerically controlled speed of the firstlaser beam is in a range from 4 m/minute to 15 m/minute.

In some embodiments, a wavelength of the third laser beam is in a rangefrom 5 μm to 15 μm, and a focus offset range of the third laser beam isless than 5 mm.

In some embodiments, a frequency of the third laser beam is in a rangefrom 10 kHz to 20 kHz, and a power of the third laser beam is in a rangefrom 10 W to 35 W.

In the foregoing description, embodiments have been described withreference to numerous specific details that may vary from implementationto implementation. The description and drawings are, accordingly, to beregarded in an illustrative rather than a restrictive sense.

The invention claimed is:
 1. A method for manufacturing an opticaleyepiece, the method comprising: directing a first laser beam from atleast one laser onto a first side of an optical waveguide material forthe optical eyepiece, wherein the first laser beam generates a firstplurality of perforations in the optical waveguide material, wherein thefirst plurality of perforations extend through the optical waveguidematerial from the first side of the optical waveguide material to asecond side of the optical waveguide material; directing a second laserbeam from the at least one laser onto the second side of the opticalwaveguide material to generate a second plurality of perforations in theoptical waveguide material, wherein the second side is opposite thefirst side, and wherein the first plurality of perforations and thesecond plurality of perforations define a perforation zone; anddirecting a third laser beam from the at least one laser at theperforation zone to singulate the optical waveguide material at theperforation zone.
 2. The method of claim 1, wherein the first laser beamand the second laser beam are sent from a same laser of the at least onelaser.
 3. The method of claim 1, wherein the first laser beam and thethird laser beam are sent from different types of lasers.
 4. The methodof claim 1, wherein at least one of the first laser beam and the secondlaser beam is sent from a diode-pumped laser.
 5. The method of claim 1,wherein the third laser beam is sent from a carbon dioxide laser.
 6. Themethod of claim 1, wherein the optical waveguide material has arefractive index greater than 1.6.
 7. The method of claim 1, wherein thefirst laser beam generates the first plurality of perforations bychemically altering a first portion of the optical waveguide material,the first portion corresponds to the first plurality of perforations,the second laser beam generates the second plurality of perforations bychemically altering a second portion of the optical waveguide material,and the second portion corresponds to the second plurality ofperforations.
 8. The method of claim 1, wherein the first laser beamgenerates the first plurality of perforations by ablating a firstportion of the optical waveguide material, the first portion correspondsto the first plurality of perforations, the second laser beam generatesthe second plurality of perforations by ablating a second portion theoptical waveguide material, and the second portion corresponds to thesecond plurality of perforations.
 9. The method of claim 1, whereinsingulating the optical waveguide material at the perforation zonecomprises heating the optical waveguide material at the perforation zoneto expand the first plurality of perforations and the second pluralityof perforations.
 10. The method of claim 1, further comprising rotatingthe optical waveguide material about an axis in a plane of the opticalwaveguide material, such that the second side faces the second laserbeam.
 11. The method of claim 1, further comprising: incising, by thefirst laser beam, a plurality of fiducial markers in the opticalwaveguide material; and using the plurality of fiducial markers to alignthe optical waveguide material with a laser generating the first laserbeam.
 12. An apparatus for manufacturing an optical eyepiece, theapparatus comprising: at least one laser that is configured to: emit afirst laser beam onto a first side of an optical waveguide material forthe optical eyepiece such that the first laser beam generates a firstplurality of perforations in the optical waveguide material, wherein thefirst plurality of perforations extend through the optical waveguidematerial from the first side of the optical waveguide material to asecond side of the optical waveguide material; emit a second laser beamonto the second side of the optical waveguide material to generate asecond plurality of perforations in the optical waveguide material,wherein the second side is opposite the first side, and the firstplurality of perforations and the second plurality of perforationsdefine a perforation zone; and emit a third laser beam at theperforation zone to singulate the optical waveguide material at theperforation zone.
 13. The apparatus of claim 12, wherein the first laserbeam and the second laser beam are emitted from a same laser.
 14. Theapparatus of claim 12, wherein the first laser beam and the second laserbeam are emitted from a same type of laser.
 15. The apparatus of claim12, wherein the first laser beam and the third laser beam are emittedfrom different types of lasers.
 16. The apparatus of claim 12, whereinat least one of the first laser beam and the second laser beam isemitted from a diode-pumped laser.
 17. The apparatus of claim 12,wherein the third laser beam is sent from a carbon dioxide laser. 18.The apparatus of claim 12, wherein the first laser beam generates thefirst plurality of perforations by chemically altering a first portionof the optical waveguide material, the first portion corresponds to thefirst plurality of perforations, the second laser beam generates thesecond plurality of perforations by chemically altering a second portionof the optical waveguide material, and the second portion corresponds tothe second plurality of perforations.
 19. The apparatus of claim 12,wherein the first laser beam generates the first plurality ofperforations by ablating a first portion of the optical waveguidematerial, the first portion corresponds to the first plurality ofperforations, the second laser beam generates the second plurality ofperforations by ablating a second portion the optical waveguidematerial, and the second portion corresponds to the second plurality ofperforations.
 20. The apparatus of claim 12, further comprising a motoroperatively coupled to the optical waveguide material and configured torotate the optical waveguide material about an axis in a plane of theoptical waveguide material, such that the second side of the opticalwaveguide material faces the second laser beam.
 21. The method of claim1, wherein the second plurality of perforations extend through theoptical waveguide material from the second side of the optical waveguidematerial to the first side of the optical waveguide material.
 22. Themethod of claim 1, wherein a spacing between the first plurality ofperforations and the second plurality of perforations is less than aspecified accuracy tolerance.
 23. The method of claim 22, wherein thespecified accuracy tolerance is based on a computer numerical control(CNC) laser module accuracy tolerance or based on a CNC stage accuracytolerance.
 24. The apparatus of claim 12, wherein the at least one laseris configured to generate the second plurality of perforations so thatthe second plurality of perforations extend through the opticalwaveguide material from the second side of the optical waveguidematerial to the first side of the optical waveguide material.
 25. Theapparatus of claim 12, wherein the at least one laser is configured togenerate the first plurality of perforations and the second plurality ofperforations so that a spacing between the first plurality ofperforations and the second plurality of perforations is less than aspecified accuracy tolerance.
 26. The apparatus of claim 25, wherein thespecified accuracy tolerance is based on a computer numerical control(CNC) laser module accuracy tolerance or based on a CNC stage accuracytolerance.
 27. A method for manufacturing an optical eyepiece, themethod comprising: directing a first laser beam from at least one laseronto a first side of an optical waveguide material for the opticaleyepiece, wherein the first laser beam generates a first plurality ofperforations in the optical waveguide material; directing a second laserbeam from the at least one laser onto a second side of the opticalwaveguide material to generate a second plurality of perforations in theoptical waveguide material, wherein the second side is opposite thefirst side, and wherein the first plurality of perforations and thesecond plurality of perforations define a perforation zone; directing athird laser beam from the at least one laser at the perforation zone tosingulate the optical waveguide material at the perforation zone;incising, by the first laser beam, a plurality of fiducial markers inthe optical waveguide material; and using the plurality of fiducialmarkers to align the optical waveguide material with a laser generatingthe first laser beam.